1. Field of the Invention
The present invention relates generally to the field of minimally invasive, image-guided excisional biopsy devices and processes, and more particularly pertains to an RF loop probe and process useful for excision and removal of cancerous lesions from soft tissue, including breast tissue and other other types of soft tissue such as the liver and the lungs.
2. Background of the Invention
The subject invention provides for removal of benign and malignant neoplasms of the breast in a less invasive manner than current surgical methods. Once a lesion is detected through either a physical exam or a mammogram, a biopsy is performed to diagnose whether the detected abnormality is malignant or benign. The tissue for this diagnostic biopsy can be acquired through a fine needle aspiration, core biopsy, vacuum-assisted core biopsy, or an open surgical biopsy. The tissue is then examined by a pathologist to determine whether the lesion is benign or malignant. If the lesion is determined to be benign, the patient may desire that the lesion be removed, especially if the lesion is palpable. If the lesion is malignant, the patient currently has two primary treatment options, 1) mastectomy or 2) breast conserving therapy, i.e. lumpectomy, followed by radiation therapy.
Breast conserving therapy is indicated for patients with Stage T1 or T2 cancers, which are less than 5 cm in greatest dimension. To localize the lesion within the breast, a radiologist places a guide wire under x-ray or ultrasound guidance, ideally with the distal tip of the guidewire in the center of the lesion and the proximal end of the wire protruding from the breast. The patient is then transported to the operating room. The surgeon uses the guidewire to find the lesion in the breast and to excise a lump of tissue including the cancer and a margin of normal tissue surrounding the cancer. Typically the surgeon uses a scalpel and/or an electrosurgical probe to cut a one-piece specimen and manage bleeding. The lump is removed and transported to the pathologist, who examines the margins of the specimen to determine whether the cancer has been completely removed. If the pathologists finds cancer cells too close to the edge of the specimen, he or she will recommend a re-excision, and the patient must have a second open surgical procedure to remove more tumor.
There are several problems with conventional breast conserving therapy which the present invention addresses. The first is localization of the lesion, i.e. needle localization. Because of technical challenges associated with placement of the needle, often the radiologist does not place the guide wire through the center or the lesion. It is particularly difficult to place the needle at the correct depth. Also, when the guidewire is placed under x-ray guidance, the breast is compressed. When the breast is decompressed for the open surgical excision, the guidewire can migrate in the breast, resulting in inaccurate placement thereof. Finally, the guidewire placement procedure is uncomfortable to the patient and logistically challenging because the procedure must be coordinated with the time of surgery. Often, the easiest path for the radiologist to place the guidewire is different from the best surgical approach, so the surgeon cannot follow the guidewire down to the lesion.
A second problem with current open lumpectomy is the highly variable re-excision rate, which can be anywhere from 5% to 50% depending upon the surgeon, the disease stage, and whether the lesion is diagnosed as malignant before the surgery. This high re-excision rate can be prescribed to the uncertain nature of the location of cancerous vs. healthy tissue. This uncertainty is a result of inaccurate guidewire placement and difficulty discerning the full extent of the disease, especially with non-palpable lesions. To compensate for the imprecision in determining the extent of the disease, the surgeon must take much more tissue than would be required if the full extent of the cancer could be imaged in real-time. The surgeon must also make a large incision to provide access for his/her hands and scalpel to excise the lesion. This results in a large scar and a great amount of tissue being removed, which both negatively impact cosmesis.
Finally, because the procedure is so invasive, the surgery must be performed in an operating room, resulting in higher overhead costs. The patient must be anesthetized with either conscious sedation and local anesthesia or general anesthesia, which can lead to further complications.